Dennis Had Inspire Amps

[x3workshop]

Originally Posted by Musica Amantem

Peter and Rosco65,

Thanks for your insights. I'm aware your conclusions and respective final implementations came after serious efforts reading, asking and trying, as well as investing ... so I really appreciate your kind and unselfish assistance. But, you guys are way ahead of me in this topic. So let me try to make this as simple as it is for me to be able to grasp these concepts which should lead me to a tailored action plan. If I'm wrong on the following conclusions (probably), kindly let me know.

1. The L12 is sealed and does not offer speaker binders, so it is for music but cannot be connected at high-level. I assume low-level inputs are good enough.

2. The LP-27a offers two pairs of stereo outs. I confused that with an integrated tube amp I own which only offers SUB outs. Sorry! So the bass would be stereo.

3. I have High Pass filters at 100 Hz, so I cannot cross over the SUB under that mark if I don't want to loose bass frequencies.

...

Two splitting RCA "Y"'s should do it. I just would need another pair of bass cables (mine are Blue Jeans bass cables).

This is as far as I can get for now. Thanks again. I'll give these ideas more thought, while doing some research whenever I find the time.

I had Dennis put a third set of outputs on my LP-27a specifically for using subs to augment the low end and to facilitate my desire to use the LP-27a with other monoblock amplifiers such as McIntosh MC30's and Acrosound UL II's. Works like a charm.

[Musica Amantem]

Originally Posted by x3workshop

I had Dennis put a third set of outputs on my LP-27a specifically for using subs to augment the low end and to facilitate my desire to use the LP-27a with other monoblock amplifiers such as McIntosh MC30's and Acrosound UL II's. Works like a charm.

Just to make sure again, this is how I have the SUB setup in my system:

The pair of extra outputs in my LP-27a (L + R) go into the Line-In (L + R) in the SUB (line-level connection). Then I just dial-in the cross-over knob to 100 Hz (as I have the filters at 100 Hz going into the Inspire amp). Does this sound right?

[Musica Amantem]

Originally Posted by Bombadil

Just because your Velodyne has only an 8" driver and just 160 watts, does not mean it has a flat response curve from 40-100Hz, or that it has low distortion. It could have a mid-bass bump in the 60 to 80Hz region which could make it sound boomy. Or its overall THD level might climb at a particular volume level. Some subs produce muddy bass.

Right. I'm sort of disappointed now with the Velodyne, because the more attention I pay to it, the more I feel it does not project musical bass but a boomy sound. When my mains project mid-bass, these sound much better, but not powerful enough. Instead, the SUB makes that boomy sound which I have to keep at low volumes to avoid the "noise".

I believe the conclusion is I need a really musical SUB, but I've been hesitating to get another one and end up with the same boomy results ...

[Musica Amantem]

Originally Posted by nhparrot

Have you tested the output using a SPL meter and reference tones? I use a Radio Shack SPL meter and a Rives Audio test CD to "dial in" the crossover point and volume setting on my subwoofer.

No I haven't, but I believe it is pretty easy to mix the bass volume with the mains using your ears. Also, cross-over is mathematical with the filters in the Inspire amp at 100 Hz. That is the ideal SUB range to work at with this model: 34 to 100 Hz.

I may need to find a better SUB location in the room, but since it is currently between the mains, closer to the right-hand loudspeaker, in front of the sweet-spot and aligned with both speakers' drivers plane, the booming should not exist anyway, as it is not close to any walls.

In my situation, the SUB is either booming or so quiet that it does nothing for the bass at the low volume I need to keep it to avoid that booming. I don't hear bass, but an annoying "boom boom". Ever since I implemented the filters, the mains have nicely increased their musical contributions above 100 Hz, but evidently the Inspire does not have the pep to make them play louder so the good bass above 100 Hz is there, but weak. When increasing mains' volume, mid-range and highs overcome the bass sounds above 100 Hz. If I had a musical SUB I would probably cross it at 120 Hz to fill that weak gap between 100 Hz and 120 Hz from the Inspire-supported mains. That is why I am considering a sealed Rythmik 12FG for its alleged better extension into that realm.

In any event, my SUB really sucks and the filters have made me realize this more so as the mains are much better now in the overall baseline.

[x3workshop]

Originally Posted by Musica Amantem

Just to make sure again, this is how I have the SUB setup in my system:

The pair of extra outputs in my LP-27a (L + R) go into the Line-In (L + R) in the SUB (line-level connection). Then I just dial-in the cross-over knob to 100 Hz (as I have the filters at 100 Hz going into the Inspire amp). Does this sound right?

Exactly.

[Musica Amantem]

Originally Posted by x3workshop

Exactly.

Well, thanks for getting that out of the way BTW, has anyone any experience with the other popular alternative from SVS, the SB-2000? I believe this is not servo-controlled, which is a drawback, but I've read good reviews about it.

[x3workshop]

Originally Posted by Musica Amantem

Right. I'm sort of disappointed now with the Velodyne, because the more attention I pay to it, the more I feel it does not project musical bass but a boomy sound. When my mains project mid-bass, these sound much better, but not powerful enough. Instead, the SUB makes that boomy sound which I have to keep at low volumes to avoid the "noise".

I believe the conclusion is I need a really musical SUB, but I've been hesitating to get another one and end up with the same boomy results ...

I use a Martin Logan Dynamo 700 which fits in perfectly with my setup. Very musical and controlled. No boomy bass. For my office I have a tiny pinnacle subsonic w/dual 8"s. Sealed also. It doesn't go so low, but the bass is very tight and controlled which IMO is worth the ultra low end trade off.

Experiment more with placement. May change things significantly.

[Rosco65]

Originally Posted by Musica Amantem

Still trying to decide (if at all) between Rythmik L12 and F12 SUBs, since what I have read around seems to indicate that, in smaller rooms, single 12" driver units should have enough power. Of course, the stereo effect of 2 SUBs is even better, but non-essential. The only apparent condition is to have larger than 5" drivers in the mains (my mains have single 10" Eminence drivers, so these fulfill this caveat and is the reason I'm not considering dual 8" options yet since the Eminence drivers project nice mid-bass). This would represent the first stage of a full bass sub-system build-up, spreading the investment over time.

I'm just wondering why my Velodyne, although having a single 8" driver and only 160 Watts RMS, sounds "boomy" after a certain volume level. This weekend, I'll try to stuff the front-firing port on the Velodyne to see what happens.

Another consideration is the F12 has two options: F12 and F12G, the latter a design by GR Research, which is presumably better for cross-overs above 80 Hz. Since I use the RED MOD high pass filters at 100 Hz, does this mean the 20 Hz range difference will have better extension with the F12G?

Any further orientation from Peter, Rosco65 (to complement your great original contributions under the present perspective), or anyone else with SUB experience, would be appreciated.

You're trying to balance the sound of a pair of high efficiency speakers with a single, ported 8" subwoofer with a 160 watt amp. My initial reaction is that you're overdriving this "subwoofer" and hearing the one-note boom of the bass port.

But let's see what we need from our subwoofer: let's say your mains are 95dB driven by a 6wpc (KT77 triode) amp. You're getting about 7dB from your amp, so you are looking at 102dB from each speaker. With two speakers you are looking at 105dB output above 100hz in your system.

Assuming the 160 watts from your Velodyne is truthful, we can expect 22dB of gain from your subwoofer amp. With a typical driver of efficiency of 85dB, we should see a maximum output of 107dB. That assumes that the specs from Velodyne are accurate, which I do not. A look at a current equivalent model does not give frequency response or specs. I can only assume that that this 8" vented subwoofer is not performing any sonic miracles. In other words, you don't have enough (or a high enough quality) subwoofer to match your Tektons. This is aside from the fact that many manufacturers have moved to sealed subs for music.

Now on to Rythmik: the F12 line comprises the F12 aluminum driver and the F12G paper driver designed by Danny Ritchie of GR research. The latter may not have the ultimate high power capability of the aluminum driver, but that is not really a concern for us. If we are crossing over higher or are trying to match paper-coned midbass drivers, the F12G would be my choice. If, like most users, you are using the subwoofer for HT (which is probably 90% of the subwoofer market) with a high-powered AVR, the aluminum cone in a vented enclosure might be a better choice.

On the L12 vs. F12G: The L12 uses an off-the-shelf paper driver that Brian describes as very light (good) in a sealed enclosure that is powered by a 300w Hypex amp with both stereo line level and mono LFE inputs. This amp is similar to that used in my F8 (using 300w per driver) and likely Peter's single-driver midbass speakers. The F12/F12G uses the class a/b A370 amp that also has speaker level inputs as well as more bass controls. Brian has indicated that the output specs of the L12 are the same as the F12.

Brian adds in a another forum's megathread about Rythmik subwoofers:

"Originally Posted by Flatliner View Post

F12G with paper cone uses a cast frame? whereas the paper cone driver in the LV12R (and L12/LV12 upcoming subs) use the less expensive stamped frame. Cast versus stamped frame is one of the things which I always considered as an indication of price level/ quality (though I'm very happy with the LV12R thus far). Aluminum versus paper cone in itself does not seem to matter as much (both have pro's and con's from what I have read on your site).

"The cast frame adds to the cost. I was a bit concerned that the stamp frame gasket may add too much coloration. However, this particular gasket that the supplier selects is heavier duty (thicker gauge steel). After i tested it against F12, it is close in terms of sound quality. I think the customers can hear the improvement too. The forumula that we have to make servo subs sound good are all in these entry level subwoofers. And from LV12/L12 to F12 you can get incremental improvement. In the ideal world, I would like to have everyone move to the D-, E- and F- series subs. But there are customers with limited budget. We need to do our best within that budget. It is a different challenge to us."

If you have a few days, I would recommend diving into the Rythmik megathread on the other forum, currentlfy at 1,018 pages.

My personal opinion:

Brian at Rythmik is probably the guy to go to for boutique high performance subwoofer at a reasonable cost. Both Louis Chochos and Jim Salk have used his products in their completed speakers. All models are of very high quality.

Now, when we add value to the equation things become even more compelling:

The Velodyne 8" ported subwoofer has an 8" driver driven by a 180 watt amp promising response to 32hz, all for $459 plus shipping.

The Rythmik L12 sealed subwoofer has a 12" driver driven by a 300 watt amp promising response to 18hz, all for $539 shipped in Conus. As a added bonus, the L12 is small enough to ship by parcel post (no doubt intentional to keep the shipping costs down).

In your case, simply replacing your Velodyne with an L12 sealed subwoofer would be a great leap forward at a bargain price. You could add a second L12 for stereo later. I am of the opinion that from a value standpoint, two L12's will cost about the same as a single F8 or F12G and would offer better performance in your case.

[Rosco65]

Originally Posted by Musica Amantem

No I haven't, but I believe it is pretty easy to mix the bass volume with the mains using your ears. Also, cross-over is mathematical with the filters in the Inspire amp at 100 Hz. That is the ideal SUB range to work at with this model: 34 to 100 Hz.

I may need to find a better SUB location in the room, but since it is currently between the mains, closer to the right-hand loudspeaker, in front of the sweet-spot and aligned with both speakers' drivers plane, the booming should not exist anyway, as it is not close to any walls.

In my situation, the SUB is either booming or so quiet that it does nothing for the bass at the low volume I need to keep it to avoid that booming. I don't hear bass, but an annoying "boom boom". Ever since I implemented the filters, the mains have nicely increased their musical contributions above 100 Hz, but evidently the Inspire does not have the pep to make them play louder so the good bass above 100 Hz is there, but weak. When increasing mains' volume, mid-range and highs overcome the bass sounds above 100 Hz. If I had a musical SUB I would probably cross it at 120 Hz to fill that weak gap between 100 Hz and 120 Hz from the Inspire-supported mains. That is why I am considering a sealed Rythmik 12FG for its alleged better extension into that realm.

In any event, my SUB really sucks and the filters have made me realize this more so as the mains are much better now in the overall baseline.

Two points: Your ears are probably not as good as you would like them to be when trying to dial in your subwoofers. You're flying blind and would be better using a microphone and measurement app to help you zero in. Additionally, the crossover between the sub and mains is not a brick wall filter: with 6 or 12dB/octave filters you still get a lot of output below and above the corner frequency. You may need to spread the overlap the low pass and high pass frequencies in your room and with your equipment.

Another point is to not get hung up on what you "should" be hearing and focus on what you are actually hearing. You may need to move your sub around and/or treat the room to tame some of your bass demons. I would argue that some of your boominess may be room-related and may require some specific bass trapping.

[Musica Amantem]

Rosco65 wrote: "In your case, simply replacing your Velodyne with an L12 sealed subwoofer would be a great leap forward at a bargain price. You could add a second L12 for stereo later. I am of the opinion that from a value standpoint, two L12's will cost about the same as a single F8 or F12G and would offer better performance in your case".

Excellent points made based on your sensible arguments. This sounds like a plan! Thanks for the thorough explanation, again.